Transport of Subsurface Chemicals under Nonequilibrium Sorption Conditions

An increasing weight of evidence has indicated that under certain conditions chemicals above background levels in soils may not be easily released and thus may not have an adverse environmental effect. This has led to a broadening body of knowledge about the extent and rate of release (ROR) of hydrocarbons from contaminated soil. A groundwater fate and transport screening model was developed that incorporates chemical ROR kinetics for the express purpose of identifying where and when the incorporation of ROR information may affect model predictions, as well as site remediation and management decisions. The results from this evaluation indicate that at many sites the incorporation of chemical release kinetics in such models leads to important differences in predicted chemical concentrations that reach a receptor. This paper also discusses how ROR information may be used to improve model predictions at a site, how to evaluate the importance of ROR at a site, and how to identify the most influential input parameters.